GRE Subject Test: Biochemistry, Cell, and Molecular Biology : Help with Light Reactions
Study concepts, example questions & explanations for GRE Subject Test: Biochemistry, Cell, and Molecular Biology
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Example Questions
Example Question #1 : Help With Light Reactions
Which molecule transfers electrons from photosystem II to photosystem I?
Ferredoxin
Cytochrome c
Plastocyanin
NADP+
Plastocyanin
Photosystems I and II are each capable of conducting electrons, with photosystem II handing off electrons to photosystem I. This is accomplished by the electron carrier molecule plastocyanin.
Example Question #2 : Help With Light Reactions
Which product is made in photosystem I?
NADH
Glucose
ATP
NADPH
NADPH
Photosystems I and II are responsible for the light-dependent reactions of photosynthesis. These two photosystems work in tandem to create ATP and NADPH products. ATP is created in photosystem II, while NADPH is created in photosystem I.
Example Question #3 : Help With Light Reactions
What fuels ATP synthase to make ATP from ADP + Pi in the light reaction of photosynthesis?
Light excites photosystem II to split water into hydrogen and oxygen. Oxygen accumulates in the thylakoid space. Oxygen then moves down its concentration gradient from the thylakoid space to the stroma by passing through ATP synthase, fueling the synthesis of ATP
Light excites photosystem I to generate electrons that pass through the thylakoid membrane to excite ATP synthase to generate ATP
Light excites photosystem II to split water into hydrogen and oxygen. Hydrogen ions accumulate in the thylakoid space. Hydrogen moves down its concentration gradient from the thylakoid space to the stroma by passing through ATP synthase, fueling the synthesis of ATP
The mechanism by which ATP synthase is fueled is not entirely known
NADPH is formed from NADP+ reductase in the thylakoid membrane. NADPH can then donate hydrogen to ATP synthase to fuel the synthesis of ATP
Light excites photosystem II to split water into hydrogen and oxygen. Hydrogen ions accumulate in the thylakoid space. Hydrogen moves down its concentration gradient from the thylakoid space to the stroma by passing through ATP synthase, fueling the synthesis of ATP
Excitation of photosystem II splits water in the thylakoid space into hydrogen and oxygen. The hydrogen then passes through ATP synthase to move down its concentration gradient and into the stroma. Excitation of photosystem I passes electrons to NADP+ reductase to convert NADP+ to NADPH. Regeneration of NADPH is necessary for the Calvin cycle.
Example Question #45 : Cellular Metabolism
During the photosynthetic light reactions, which of the following molecules acts as the electron acceptor?
Electrons excited in photosystem I are accepted by 
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